1. Field of the Invention
The present invention relates to telecommunications protocols and more particularly to telecommunications protocols for use with personal computers and computer workstations.
2. State of the Art
Personal computers and computer workstations with modems now access a wide variety of networks. Although modem communications is generally adequate for exchanging text files, the transmission of voice, fax and video data, especially simultaneous, requires a data rate that exceeds the capabilities of most modems. The Integrated Services Digital Network (ISDN) is designed to provide what appears to the user to be one unified network satisfying all user needs. ISDN has begun to achieve significant penetration in Europe and, somewhat more slowly, in the U.S. In ISDN networks, a digital adapter serves as the communications equipment. Since the data is digital throughout the network, the function of a modem becomes unnecessary.
Early adoption of ISDN has been hampered by what may be referred to as the "chicken-egg" ISDN dilemma. The cost of ISDN technology also remains prohibitive for a broad class of users. The existing installed base of personal computers relies primarily on a standardized, low-bandwidth serial interface to achieve interconnection for telecommunications. For example, the serial port of IBM PCs and compatibles is limited to a data rate of 9.6 kbps. For higher data rates of the type required by ISDN, specialized hardware and software is required.
Furthermore, ISDN is limited to digital data. In the long term, this limitation is likely to be of only passing significance. In the short term (the next five to ten year), however, the exclusively digital nature of ISDN poses a distinct problem. The vast majority of fax machines presently in use are designed to communicate over the analog telephone network. An ISDN user, in order to retain use of such a fax machine, must then have two telecommunications lines, an ISDN line and an analog line. Clearly, the integrated nature of telecommunications envisioned in ISDN will take some time to achieve using ISDN only.
As for conventional modems, the numerous specifications required to establish a high-speed connection present an often insuperable challenge. Furthermore, because the telephone networks in the various countries of the world each have their own different standard and regulations, a conventional modem is not equipped for use in different countries. Business travelers, for example, are unable to use a single device for digital communications throughout the world, but instead must use different devices depending upon their particular location at a particular time.
A host of new telecommunications applications are becoming increasingly available. These include speech I/O, multimedia, enterprise communications, remote LAN access, intelligent telephony and video telephony. Telecommunications interconnections for these applications have thus far been developed on an ad hoc basis. In order to fully realize the benefit of these and other emerging communications technologies, a standard, versatile telecommunications interface is required. The present invention addresses the need for a telecommunications interface that allows high-performance, low-cost telecommunications platforms to support global fax, data, voice, and other data streams in an intuitive way.